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.\" $Id: elf_version.3 3639 2018-10-14 14:07:02Z jkoshy $
.\"
.Dd November 9, 2011
.Dt ELF_VERSION 3
.Os
.Sh NAME
.Nm elf_version
.Nd retrieve or set ELF library operating version
.Sh LIBRARY
.Lb libelf
.Sh SYNOPSIS
.In libelf.h
.Ft unsigned int
.Fn elf_version "unsigned int version"
.Sh DESCRIPTION
The
.Fn elf_version
function is used to query the current operating version of the ELF
library, and to inform the ELF library about the application's desired
operating version.
.Pp
If the argument
.Ar version
is
.Dv EV_NONE ,
the
.Fn elf_version
function returns the currently configured operating version for the
ELF library.
.Pp
If the argument
.Ar version
is not
.Dv EV_NONE ,
and if argument
.Ar version
is supported by the ELF library, function
.Fn elf_version
sets the library's operating version to
.Ar version ,
and returns the previous value of the operating version.
If argument
.Ar version
cannot be supported, then the
.Fn elf_version
function returns
.Dv EV_NONE .
.Sh RETURN VALUES
The
.Fn elf_version
function returns the currently configured ELF library version, or
.Dv EV_NONE
if an unsupported version is requested.
.Sh EXAMPLES
An application program would inform the ELF library about its desired
operating version and check for an error using the following code
snippet:
.Bd -literal -offset indent
if (elf_version(EV_CURRENT) == EV_NONE)
	err(EXIT_FAILURE, "ELF library too old");
.Ed
.Sh ERRORS
Function
.Fn elf_version
may fail with the following error:
.Bl -tag -width "[ELF_E_RESOURCE]"
.It Bq Er "ELF_E_VERSION"
An unsupported library version number was requested.
.El
.Sh SEE ALSO
.Xr elf 3 ,
.Xr gelf 3
